I recently needed the coordinates of the furthest point from the sea in New Zealand for my calculations at work. I thought such information had been widely known for at least a century, and went to search it in the Internet. To my surprise I didn’t find it. Instead I came across an article in the Otago Daily Times telling a story of a wine-grower’s family from Central Otago who had also been curious about this, and wanted to know if the New Zealand’s furthest inland point was in their vineyard. The article said that the couple contacted Land Information New Zealand and the geography department of the University of Otago. What I read next, really shocked me:
Surprisingly, a call to LINZ elicited the response that they didn’t know where it was, but they could survey it at the cost of megabucks. That was not an option.
Not wanting to spend millions of dollars, the farmer took a ruler, and Google Earth, and found the location.
I also would never pay megabucks for that. Instead, I downloaded the coordinates of the coastline for New Zealand from the Digital Chart of the World. These coordinates are not a State secret. They are freely available for download, and are in a plain text file. I opened the file, extracted the coastline coordinates for the South and North Islands (it was not difficult to find them in the file because these two islands are the biggest), and then wrote a small C++ program that calculates the furthest point from the coast.
I didn’t use any sophisticated C++ libraries, the program is just a couple of loops and arrays. In fact, it doesn’t have to be in C++; any language would do. I also used a little bit of maths that I had learned long ago in high school to calculate spherical distance between inland points (I assumed that the Earth is spherical; I think this approximation is sufficient within the area of the South Island).
Here is what I’ve got. The coordinates of the furthest point are: S45.08024444, E169.33355556. This is very close to the point calculated by the wine-grower. I also calculated the furthest inland point in the North Island. It is S38.69180556, E175.91597223.
It took me just a couple of hours this weekend to complete all this work on my laptop at home.
Megabucks research… oh…